There are many portable electronic devices and apparatus, especially in consumer electronics, that use a battery (cell) as their power source. The voltage supplied from the cell does not necessarily match the voltage level required in the electronic devices. Thus, a need exists to boost or convert the supplied voltage to a higher output voltage which is provided to internal circuits in the electronic devices. A typical voltage converting device employs so-called up-converter having NMOS gate transistors and capacitors for boosting voltage. In such up-converter, a voltage applied to the gate electrode of the NMOS transistor to turn on it is desired to be increased up to a level higher than the output voltage, in order to decrease on-resistance of the NMOS transistor to lower its power dissipation. Therefore, a driver such as an inverter was used, which operates between the increased voltage level and a ground level.
However, when such NMOS transistor turns off, electrical charge which has been stored in a parasitic capacitor at its gate electrode during on-status is discharged to the ground and lost. As the gate voltage of the NMOS transistor is made higher, the amount of the electrical charge lost to the ground becomes larger, resulting in high consumption of power.
Accordingly, it would be advantageous to have a voltage converting circuit having low consumption driver with maintaining low power dissipation.